【Android UI】自定义圆形Loading动画

1、创建环形loading图片

<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
android:fromDegrees="0"
android:toDegrees="360"
android:pivotX="50%"
android:pivotY="50%">

<shape android:shape="ring"
android:innerRadiusRatio="3"
android:thicknessRatio="8"
android:useLevel="false">

<size android:width="45dp"
android:height="45dp" />

<gradient android:type="sweep"
android:useLevel="false"
android:startColor="#ffaaaaaa"
android:centerColor="#ff888888"
android:centerY="0.5"
android:endColor="#ff666666" />

</shape>

</rotate>

2、通过ImageView加载loading动画
ImageView loadingImg = (ImageView) this.findViewById(R.id.loadingImg);
Animation animation = AnimationUtils.loadAnimation(this, R.anim.loading_animation);
loadingImg.startAnimation(animation);

3、动画loading_animation.xml文件如下
<?xml version="1.0" encoding="utf-8"?>
<set android:shareInterpolator="false" xmlns:android="http://schemas.android.com/apk/res/android">
<rotate
android:interpolator="@android:anim/linear_interpolator"
android:pivotX="50%"
android:pivotY="50%"
android:fromDegrees="0"
android:toDegrees="+360"
android:duration="1500"
android:startOffset="-1"
android:repeatMode="restart"
android:repeatCount="-1"/>
</set>

4、也可以通过ProgressBar来设置Loading动画
<ProgressBar
android:id="@+id/loadingProgressBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminateDrawable="@drawable/loading_ring"
android:indeterminateOnly="true"
android:indeterminateBehavior="repeat"
style="?android:attr/progressBarStyle"/>